Homework

Chapter 11: Networked Appications

Last Name: ______

First Name: ______

Due Date: ______

Directions

Place your cursor at the end of a question and hit Enter. This will place you in the Answer style. This has already been done for Part a) of Question 1.

Test Your Understanding Questions

1. a) What business problem did Papa Murphy’s face? [411]

b) How did Papa Murphy’s resolve this problem? [411]

c) What benefits did Papa Murphy’s see as a result of its choice to use Salesforce to handle this work? [411]

d) Can you think of any risks that are involved in this business choice? [411]

2. a) What is a networked application? [412]

b) What is an application architecture? [412]

c) Why do users focus on the application layer? [413]

3. Create a table. The first column should be client device (dumb terminal, PC, etc.). The second column should be the technical advance embodied in the client. The third should be networking advances associated with the client. The fourth and last should be new networked applications made possible by the client and networking. [413-414]

4. What advance made the client/server application architecture possible? [414]

5. a) Why are hackers now focusing on taking over applications? [415-416]

b) What are root privileges? [415]

c) Why is the explosion of applications and small mobile devices a particular concern? [416]

6. a) Distinguish among the major standards for e-mail bodies. [417-418]

b) In traditional e-mail, when a station sends a message to its mail server what standard does it use? [418]

c) When the sender’s mail server sends the message to the receiver’s mail server what standard does it use? [418]

d) In traditional e-mail, when the receiver’s e-mail client downloads new mail from its mail server what standards are it likely to use? [419]

e) What is Web-enabled e-mail? [419]

f) What do you think are the advantages of a Web-enabled e-mail system? [419]

7. a) What is the main tool of firms in fighting viruses and Trojan horses in e-mail attachments? [419]

b) Why does filtering on the user’s PC often not work? [419-420]

c) What options do firms have for where antivirus filtering should be done? [420]

d) According to the principle of defense in depth, how should firms do antivirus filtering? [420]

8. a) What is VoIP? [421]

b) What is the promise of VoIP? [421]

c) What two devices can be used by VoIP callers? [421]

d) What is the purpose of a media gateway? [421]

e) Why is having a media gateway in a VoIP system important? [421]

f) Does the media gateway translate signaling transmissions or transport transmissions? [421]

9. a) What are the two major protocols for VoIP signaling? [422]

b) Which of these protocols is growing rapidly? [422]

c) Describe how SIP initiates a communication session. [422-423]

10. a) What is the purpose of a VoIP codec? [423]

b) Some codecs compress voice more. What do they give up in doing so? [423]

c) In a VoIP transport packet, what is the application message? [423-424]

d) Does a VoIP transport packet use UDP or TCP? Explain why. [424]

e) What two problems with UDP does RTP fix? [424]

f) List the headers and messages in a VoIP transport packet, beginning with the first packet header to arrive at the receiver. (Hint: See Figure 11-9.) [423]

11. a) Distinguish between HTTP and HTML. [425]

b) You are downloading a webpage that has six graphics and two sound clips. How many request–response cycles will be needed? [425-426]

c) What is the syntax of the first line in an HTTP request message? [426]

d) What is the syntax of subsequent fields? [426]

e) What is the syntax of the first line in an HTTP response message? [427]

f) What do the MIME header fields tell the receiving process? [427]

g) Why is this information necessary? [427]

h) How is the start of the attached file indicated? [427]

12. a) What is software as a service? [428]

b) Why is the word service in SaaS? [428]

c) What do you think are some advantages of storing files on Google Docs services? [429]

13. a) What is cloud computing? [429]

b) What is an organization that provides cloud services called? [429]

14. a) Describe how Software as a Service (SaaS) works. [430]

b) Describe how cloud SaaS works. [430]

c) What are the four main attractions of cloud SaaS? [430-431]

d) What are the four issues that cloud SaaS raises? [431]

15. a) Is utility computing a new phenomenon? [431]

b) Describe how utility computing works. [432]

c) Why was “utility computing” given this name? [432]

d) What provisioning problems might a company face if it runs its own data center? [432]

16. a) What are the four main attractions of cloud utility computing? [432-433]

b) What are the issues facing cloud utility computing? [433]

17. a) What three major factors have contributed to the popularity of cloud computing? [433-434]

b) How has the Internet contributed to the popularity of cloud computing? [433]

18. Briefly explain how computers that use virtualization work. [434-435]

19. What major issue must a company consider when deciding whether to use cloud computing? [436]

20. a) What is a service-oriented architecture? [436]

b) What do service objects do? [436]

21. a) What is the benefit of reuse? [437]

b) Why do SOAs make reuse more likely? [437]

c) What is language independence? [437]

d) In what sense are SOAs language-independent? [437]

e) Why is language independence good? [437]

22. a) What are Web services? [438]

b) Distinguish between SOAs and Web services. [438]

c) What is the function of SOAP? [438]

d) Why are SOAP messages encoded in XML rather than HTML? [439]

e) What is the function of WSDL? [440]

f) What is the function of UDDI? [440]

23. How are service-oriented architectures, Web services, and SOAP related? [440]

24. a) What are peer-to-peer (P2P) applications? [441]

b) How are P2P applications better than traditional server-centric client/server applications? [441-442]

c) How are they not as good? [441-442]

25. a) Distinguish between client/server file retrieval and P2P file sharing. [443-444]

b) What are the problems with each? [443-444]

c) How does BitTorrent differ from the common P2P file sharing model? [444]

d) Explain the steps of BitTorrent operation. [444-446]

e) In BitTorrent, what is an index website? [444]

f) What are .torrent files? [444]

g) In BitTorrent, what is a tracker? [444]

h) In BitTorrent, what is a swarm? [444]

i) What security concerns must firms address if they plan to use BitTorrent? [446]

j) What is the main advantage of BitTorrent file sharing? [446]

26. a) What is Skype? [446]

b) Do you have to pay a fee to make calls using Skype? Explain. [446]

c) What is the most popular P2P VoIP service? [446]

27. a) List and define Skype’s three main elements. [447]

b) Explain how login works in Skype. [448]

c) What is a directory search in Skype? [448]

d) Which element of the Skype network is in charge of signaling? [448]

e) Which element of the Skype network is in charge of transport? [448]

f) Which of Skype’s three steps is done P2P? [448]

g) Compare Skype and traditional voice over IP in terms of whether login, signaling, and transport are P2P or whether they use servers. [448]

28. a) Why is Skype’s use of proprietary software problematic?

b) What problem is there with Skype’s encryption for confidentiality? [448]

c) Does Skype control who can register a particular person’s name? [449]

d) Why do firewalls have a difficult time controlling Skype? [449]

e) Does Skype’s file transfer mechanism work with most antivirus programs? [449]

f) Overall, what is the big problem with Skype? [449]

29. How does SETI@home make use of idle capacity on home PCs? [449]

30. Explain how P2P applications may use facilitating servers yet still be called P2P applications. [450]

End-of-Chapter Questions

Thought Questions

1. Do you think that pure P2P architectures will be popular in the future? Why or why not?

2. Come up with a list of roles that facilitating servers can play in P2P applications. This will require you to read through the section on P2P applications carefully. You should also try to think of an example not in the text.

Troubleshooting Question

1. You perform a BitTorrent search and get no responses. List several possible causes. Then describe how you would test each.